The /change_hook url is a magic URL which will accept HTTP requests and translate
them into changes for buildbot. Implementations (such as a trivial json-based endpoint
and a github implementation) can be found in master/buildbot/status/web/hooks. 
The format of the url is /change_hook/DIALECT where DIALECT is a package within the
hooks directory. Change_hook is disabled by default and each DIALECT has to be enabled
separately, for security reasons
   
An example WebStatus configuration line which enables change_hook and two DIALECTS:
     c['status'].append(html.WebStatus(http_port=8010,allowForce=True,
                             change_hook_dialects={
                                     'base': True,
                                     'github': {'option1':True,
                                                 'option2':False}}))
   Within the WebStatus arguments, the change_hook key enables/disables the module
and change_hook_dialects whitelists DIALECTs where the keys are the module names
and the values are optional arguments which will be passed to the hooks.
   
The post_build_request.py script in master/contrib allows for the submission of an arbitrary change request. Run 'post_build_request.py –help' for more information. The 'base' dialect must be enabled for this to work.